title: A bioassay for the detection of perchlorate in the ppb range.
abstract: A bioassay for the determination of ppb (μg·L(-1)) concentrations of perchlorate has been developed and is described herein. The assay uses the enzyme perchlorate reductase (PR) from the perchlorate-reducing organism Dechloromonas agitata in purified and partially purified forms to detect perchlorate. The redox active dye phenazine methosulfate (PMS) is shown to efficiently shuttle electrons to PR from NADH. Perchlorate can be determined indirectly by monitoring NADH oxidization by PR. To lower the detection limit, we have shown that perchlorate can be concentrated on a solid-phase extraction (SPE) column that is pretreated with the cation decyltrimethylammonium bromide (DTAB). Perchlorate is eluted from these columns with a solution of 2 M NaCl and 200 mM morpholine propane sulfonic acid (MOPS, pH 12.5). By washing these columns with 15 mL of 2.5 mM DTAB and 15% acetone, contaminating ions, such as chlorate and nitrate, are removed without affecting the bioassay. Because of the effect of complex matrices on the SPE columns, the method of standard additions is used to analyze tap water and groundwater samples. The efficacy of the developed bioassay was demonstrated by analyzing samples from 2-17000 ppb in deionized lab water, tap water, and contaminated groundwater.
authors.affiliation: Department of Plant and Microbial Biology, The University of California, Berkeley, California 94820, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Heinnickel
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Smith
authors.forename: Jonathan
authors.initials: J
authors.lastname: Koo
authors.forename: Susan M
authors.initials: SM
authors.lastname: O'Connor
authors.forename: John D
authors.initials: JD
authors.lastname: Coates
mesh_terms: D001681:Biological Assay; D004784:Environmental Monitoring / Q000379:methods*; D009243:NAD / Q000032:analysis / Q000378:metabolism; D010088:Oxidoreductases / Q000032:analysis / Q000378:metabolism; D010472:Perchlorates / Q000032:analysis* / Q000378:metabolism; D043362:Rhodocyclaceae / Q000201:enzymology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D014881:Water Supply / Q000032:analysis
chemical_list: D010472:Perchlorates; D014874:Water Pollutants, Chemical; D009243:NAD; D010088:Oxidoreductases; C494474:perchlorate